dibble vs trepan

dibble

verb
  • To use a dibble; to make holes in the soil. 

  • To make holes or plant seeds using, or as if using, a dibble. 

  • To dib or dip frequently, as in angling. 

noun
  • A pointed implement used to make holes in the ground in which to set out plants or to plant seeds. 

  • A police officer, especially one serving with Greater Manchester Police. 

  • Preceded by the: the police. 

trepan

verb
  • To create a large hole by making a narrow groove outlining the shape of the hole and then removing the plug of material remaining by less expensive means. 

  • To use a trepan; to trephine. 

noun
  • A tool used to bore through rock when sinking shafts. 

  • A surgical instrument used to remove a circular section of bone from the skull; a trephine. 

How often have the words dibble and trepan occurred in a corpus of books? (source: Google Ngram Viewer )